Foot operated hydraulic pump



United States Patent 3,301,190 FOOT OPERATED HYDRAULIC PUMP John T.Gondek, Minneapolis, Minn., assignor to Oil- Dyne, Inc., a corporationof Minnesota Filed Dec. 28, 1964, Ser. No. 421,315 2 Claims. (Cl.103-42) This invention relates to an improvement in foot operatedhydraulic pump and deals particularly With a simple and effective pumpuseful in supplying fluid under high pressure to various instruments anddevices such as to operate hypodermic syringes used by veterinarians andthe like.

An object of the present invention resides in the provision of a simplepump having a reciprocal pump piston against which considerable forcemay be exerted by means of a foot actuated pedal or lever. The operatinglever projects laterally from the pump housing and is pivoted to thehousing on an axis in a plane substantially normal to the axis of thepiston or plunger. The piston extends from the housing and is engaged bya roller supported by the foot lever on an axis parallel to the pivotaxis of the lever. The distance between the axes of the lever and theroller is short relative to the length of the foot lever, therebymultiplying the force exerted upon the foot lever.

A further feature of the present invention resides in the provision of apump housing having a removable cover plate, the cylinder supporting thepiston extending into the housing and the interior of the housing onboth sides and above the cylinder forming a fluid reservoir. A diaphragmof a flexible nature is supported between the top cover plate and theremainder of the housing to provide a liquid chamber which may vary insize. An air chamber is provided between the cover plate and thediaphragm, and a vent aperture is provided between the air chamber andthe outer atmosphere to permit the flexing of the diaphragm with changesin the volume of liquid within the reservoir.

A further feature of the present invention resides in the provision of afoot pump of the type described in which the piston is normally urged inan outward direction by spring pressure and is urged inwardly bymovement of the foot lever. During the power stroke of the piston,liquid under pressure is forced past a check valve to the operateddevice. Liquid returns from the operated device to the reservoir. Duringthe return stroke of the piston, liquid is drawn from the reservoir intothe cylinder past another check valve.

-A feature of the present invention resides in the provision of a footoperated pump particularly designed for use in a closed system where alow volume of liquid under high pressure is required. In the preferredform of invention, about one-half of a cubic inch of liquid is pumpedduring each power stroke, but the liquid is pumped under a pressure ofseveral hundred pounds per square inch. For example, the relief valvewhich permits the bypassing of the oil under abnormal pressureconditions may be set to open at eighteen hundred pounds per square inchpressure. The pump normally delivers fluid under pressure up to thisamount before bypassing.

These and other Objects and novel features of the present invention willbe more clearly and fully set forth in the following specification andclaims.

In the following specification and claims;

FIGURE 1 is a side elevational view, partly in section, showing the pumpconstruction.

FIGURE 2 is a horizontal sectional View through the pump, a portion ofthe operating foot lever being shown in top plan.

The pump A includes an open top housing having a bottom closure plate 11and upwardly extending peripheral walls 12 thereupon which terminatein aflat ice upper surface 13. A mounting flange 14 projects forwardly fromthe lower portion of the housing and is provided with spaced apertures15 therethrough for the accommodation of mounting bolts. A mountingflange 16 also extends rearwardly from the lower portion of the housing10 and is provided with an aperture 17 designed to accommodate amounting bolt. Reinforcing gusset plates 19 connect the flange 16 withthe side walls 12, the gusset plates 19 being in spaced relation alongopposite sides of the generally rectangular flange 16.

A substantially semi-cylindrical boss 20 extends from front to rear ofthe housing on the bottom closure plate 11. The front portion of theperipheral wall 12 is greatly thickened as indicated at 21 to providespace for a pair of check valves and a pressure relief valve. Acylindrical bore 22 extends into the boss 20 from the rear side of thehousing, and is open to atmosphere above the flange 16 and between thegusset plates 19. A piston or plunger 23 is axially slidable in thecylindrical bore 22. The forward end of the piston 23 is provided withan axial cylindrical socket 24 which terminates short of the rear orouter extremity 25 of the piston 23. An axial socket 26 is also providedin the thickened wall portion 21 at the end of the cylindrical bore 22.A spring 27 is interposed between the base of the socket 26, and thebase of the piston socket 24, the spring 27 urging the piston 23rearwardly or outwardly from the housing.

A cover plate 29 having a slightly hollow under surface 30, and having adownwardly extending peripheral flange 31 terminating in a commonhorizontal plane is supported upon the top of the housing 10. The coverplate 29 corresponds in outline shape to the shape of the generallycylindrical upper end of the housing 10. A flexible diaphragm 32 isclamped between the cover plate 29 and the upper surface 13 of thehousing 10 by cap screws 33 or the like. A vent passage 34 is providedin the closure plate 29 to permit the passage of air into the spacebetween the diaphragm 32 and the cover plate 29. As a result, thediaphragm may be flexed by changes in volume of the liquid contained.

A pair of parallel arms, one of which is shown at 35, project rearwardlyfrom the walls 12 of the housing 10, the arms 35 being joined alongtheir lower edges to the gusset plates 19 for support thereby. The arms35 are on opposite sides of a vertical plane through the axis of thecylindrical bore 22. A foot pedal indicated in general by the numeral36-extends between the spaced arms 35 and is pivotally connected theretoby a pivot pin 37. The foot pedal 36 is shown generally triangular ortapered form being widest at the end adjoining the pump body andsubstantially narrower at the free outer end. In the form illustrated,the pedal 36 is somewhat similar to an eye beam in vertical section,including a peripheral web 39 of substantial width, and a thinner web 40enclosed by the peripheral edge 39. A foot engaging end 41 is supportedupon the rear end of the pedal 36, the member 41 preferably having aconvex upper surface 42 against which the shoe of the operator mayengage regardless of the angularity of the foot pedal. Reinforcinggussets 43 extend from opposite sides of the wider foot engagingend 41to strengthen the structure.

The foot pedal 36 is provided with a forward projection 44 extendingforwardly from the upper surface of the pedal to engage inclined lug 45on the center portion of the housing wall 12 between the arms 35. Theengagement of the projection 44 with the lug 45 limits the pivotalmovement of the foot pedal 36 in a counterclockwise dithe roller. Theroller 47 is positioned to engage the rear or outer end 25 of the piston23 to provide a relatively frictionless engagement between the footpedal 36 and the piston 23.

Thus it will be seen that by applying downward pressure on the footplate 41 of the foot lever 36, the piston 23 may be moved axially in adirection to force fluid from the cylinder or cylindrical bore 22.Suitable sealing rings 48 are provided in a peripheral groove 50communicating with the bore 22 to seal the piston 23 with respect to thecylinder.

As indicated in FIGURE 1 of the drawings, a vertical passage 52 extendsupwardly from the socket 26 in a communication with relatively largediameter bore 53, the tapered lowered end 54 of the bore 53 serving as avalve seat for a valve ball 55. The valve ball 55 is held against thevalve seat 54 by means of a plunger 56 slidable in the bore 53 andhaving peripheral grooves 57 to permit the bypass of fluid when the ball55 is not engaged with its valve seat 54. A plug 59 is threaded into theupper end of the bore 53 and includes a multi-sided aperature 60extending therethrough which serves as a fluid passage as well as ameans of receiving an Allen wrench or the like for rotating the plug 59.A spring 61 is interposed between the plug 59 and the plunger 56, thespring encircling an upwardly extending shank forming a part of theplunger for holding the spring and plunger aligned. The plunger 56 isprovided with a concave lower end 62 to accommodate the valve ball 55.The valve ball 55 forms a pressure relief valve which will open when thepressure in the socket 26 reaches a predetermined maximum in order topermit the bypass of liquid past the valve. As will be noted, the upperend of the bore 53 is open to the reservoir which is indicated in thedrawings by the numeral 63.

As indicated in FIGURE 2 of the drawings, a passage 64 extends from thecylindrical bore 22 to a right angularly extending larger diameter bore65 extending into the housing from the rear thereof. The bore 65 isconnected with an axially extending small diameter passage 66 by atapered valve seat 67. A valve plunger 69 having a longitudinallygrooved peripheral surface is slidably supported in the bore 65 and isprovided with a tapered end 70 designed to seat against the valve seat67. An ring 71 is provided in a groove in the tapered end 70 to preventleakage between the plunger and the seat when the valve plunger is inclosed position.

The valve plunger 69 is normally held against its seat 67 by a spring 72which has one end extending into the socketed end 73 of the plunger 69,and the other end of which extends into the socketed end 74 of aremovable plug 75. Thus the plunger 69 forms a check valve capable ofopening during the return stroke of the piston 23. As noted, the passage66 leads to the reservoir chamber 63, while the opposite side of theplunger 69 is subject to pressure in the passage 64 communicating withthe cylinder 22.

An additional passage 76, aligned with the passage 64, communicates withthe interior of the cylinder 22. The passage 76 is connected to a largerdiameter bore 77 leading through the wall 12 of the housing by a taperedvalve seat 79. A plunger 80 having a grooved outer surface is slidablein the bore 77 and is provided with a tapered end 81 designed to seatagainst the valve seat 79. An O-ring 82 is supported by the tapered end80 to form an effective seal between the plunger and the valve seat.

The plunger 80 is normally held against the valve seat by a spring 83which extends into the socketed end 84 of the plunger 80 and the opposedsocketed end 85 of a hollow screw fitting 86. The fitting 86 projectsfrom the housing 10 and is designed to accommodate a pressure hose forpipes.

An internally threaded passage 87 extends through the wall 12 of thehousing 10 into communication with reserend is designed to accommodate apressure hose or pipe through which liquid may flow into the reservoir63.

An internally threaded passage 90 extends through the casing wall 12 inopposed relation to the passage 87 and is designed to accommodate ascrew plug 91. The plug 91 is provided to facilitate the filling of thehousing.

The operation of the pump is believed readily understandable from theforegoing description. In usual practice, the fitting 86 is connected bya suitable pressure pipe or hose to an instrument or apparatus requiringa small volume of hydraulic fluid to operate where high pressure isusually required. The fitting 89 is connected by a suitable pressurehose or the like to the outlet of the instrument or other apparatus.Downward pressure upon the treadle and 41 of the foot pedal 36 swingsthis foot lever in a clockwise direction, the roller 47 engaging againstthe end of the plunger or piston 23, and urging the piston to the leftas viewed in the drawings. This action causes fluid under pressure toopen the discharge valve 80 and flow past this valve into the hoseconnected to the fitting 86.

When pressure on the foot pedal 36 is released, the foot pedal isreturned to its original position by the spring 27. Movement of thepiston 23 to the right as viewed in the drawings, creates a source ofpartial vacuum in the cylinder 22 which is communicated through thepassage 64 to the bore 65. This causes the valve plunger 73 to open,allowing hydraulic liquids to be drawnthrough the pass age 66, past theplunger 73 and the passage 64 into the cylinder 22.

In actual practice the pump is filled by turning the housing on its sideand filling the reservoir 63. When fluid is pumped from the reservoir bythe piston 23, the diavoir 63. The fitting 89 is hollow, and the outerthreaded phragm may flex downwardly to some extent. In other instances,such as during filling the diaphragm may flex in the opposite direction.The diaphragm permits fluid to be forced from, or returned to, thereservoir.

In the event the driven unit fails to function so that abnormalpressures are built up within the cylinder 22, the pressure relief valveball 55 may open to permit the bypass of fluid back into the reservoir63.

In accordance with the patent statutes, the principles of constructionand operation of this improvement in Foot Operated Hydraulic Pump havebeen described, and while an endeavor has been made to set forth thebest embodiment thereof, it should be understood that changes may bemade within the scope of the following claims without departing from thespirit of the invention.

The claims:

1. A foot actuated pump comprising:

a housing including a reservoir,

a cylinder in said housing having one end open to atmosphere, thecylinder having a generally hori zontal axis,

a piston slidable in said cylinder and including means projecting fromsaid open end,

a foot lever pivotally connected to said housing on a generallyhorizontal axis above said cylinder and in a plane normal to the axis ofthe cylinder,

roller means on said foot lever beneath said pivot axis and parallelthereto engaging the projecting end of said piston and operable to movesaid piston toward the other end of said cylinder upon pivotal movementof said foot lever,

cooperable means on said lever and on said housing limiting pivotalmovement of said foot lever in a direction to limit outward movement ofsaid piston,

resilient means normally urging said piston against said means on saidfoot lever,

said housing having an outlet passage from said other end of saidcylinder, and said housing including an inlet passage from saidreservoir to said other end of said cylinder and including a check valvepermitting a flow of liquid to, but not from, said cylinder, and

said housing including a separate return passage communicating with saidreservoir,

said housing including a diaphragm extending across said housingdividing the interior of the housing into a liquid chamber and an airchamber, said housing including a vent opening connecting said airchamber with atmosphere.

2. A foot actuated pump including:

a housing including a reservoir,

:1 cylinder in said housing having an end open to atmosphere, thecylinder axis being substantially horizontal,

a piston slidably supported in said cylinder,

resilient means urging said piston toward the open end of said cylinder,

21 foot lever pivotally supported by said housing,

means on said foot lever engaging said piston for urging said pistontoward the other end of said piston,

said housing including an inlet passage from said reservoir to saidother cylinder end and including a check valve permitting liquid to flowto, but not from, said cylinder,

said housing including an outlet passage from said other cylinder endincluding a check valve permitting liquid to flow from, but not to, saidcylinder,

said housing including a return passage communicating with saidreservoir,

a flexible diaphragm extending across said housing near the top thereofdividing the interior of said housing into a liquid chamber and an airchamber, and

said housing including an air vent'from said air chamber to atmosphere.

References Cited by the Examiner UNITED STATES PATENTS 974,988 11/ 1910Northam 10341 1,809,814 6/1931 Schutt 103-41 2,781,166 2/1957 Flood etal. 230-218 2,873,688 2/ 1959 Elder 103223 3,076,314 2/1963 Stromberg230-218 3,199,458 8/1965 Hoehn 103-42 DONLEY J. STOCKING, PrimaryExaminer.

MARK NEWMAN, Examiner. W. J. KRAUSS, Assistant Examiner.

1. A FOOT ACTUATED PUMP COMPRISING: A HOUSING INCLUDING A RESERVOIR, ACYLINDER IN SAID HOUSING HAVING ONE END OPEN TO ATMOSPHERE, THE CYLINDERHAVING A GENERALLY HORIZONTAL AXIS, A PISTON SLIDABLE IN SAID CYLINDERAND INCLUDING MEANS PROJECTING FROM SAID OPEN END, A FOOT LEVERPIVOTALLY CONNECTED TO SAID HOUSING ON A GENERALLY HORIZONTAL AXIS ABOVESAID CYLINDER AND IN A PLANE NORMAL TO THE AXIS OF THE CYLINDER, ROLLERMEANS ON SAID FOOT LEVER BENEATH SAID PIVOT AXIS AND PARALLEL THERETOENGAGING THE PROJECTING END OF SAID PISTON AND OPERABLE TO MOVE SAIDPISTON TOWARD THE OTHER END OF SAID CYLINDER UPON PIVOTAL MOVEMENT OFSAID FOOT LEVER, COOPERABLE MEANS ON SAID LEVER AND ON SAID HOUSINGLIMITING PIVOTAL MOVEMENT OF SAID FOOT LEVER IN A DIRECTION TO LIMITOUTWARD MOVEMENT OF SAID PISTON, RESILIENT MEANS NORMALLY URGING SAIDPISTON AGAINST SAID MEANS ON SAID FOOT LEVER, SAID HOUSING HAVING ANOUTLET PASSAGE FROM SAID OTHER END OF SAID CYLINDER, AND SAID HOUSINGINCLUDING AN INLET PASSAGE FROM SAID RESERVOIR TO SAID OTHER END OF SAIDCYLINDER AND INCLUDING A CHECK VALVE PERMITTING A FLOW OF LIQUID TO, BUTNOT FROM, SAID CYLINDER, AND SAID HOUSING INCLUDING A SEPARATE RETURNPASSAGE COMMUNICATING WITH SAID RESERVOIR, SAID HOUSING INCLUDING ADIAPHRAGM EXTENDING ACROSS SAID HOUSING DIVIDING THE INTERIOR OF THEHOUSING INTO A LIQUID CHAMBER AND AN AIR CHAMBER, SAID HOUSING INCLUDINGA VENT OPENING CONNECTING SAID AIR CHAMBER WITH ATMOSPHERE.